1Spray a 13x18 sheet pan with non-stick cooking spray.
2Prepare the homemade fajita seasoning blend by combining 2 teaspoons of ground cumin, 2 teaspoons of chili powder, 1 teaspoon of onion powder, 1 teaspoon of salt, and 1 teaspoon of red pepper flakes in a small bowl.
3Stir the seasoning blend and set aside.
4Slice four boneless, skinless chicken breasts into even strips, approximately 1/4 inch thick and 2 inches long.
5Add the sliced chicken to a large mixing bowl.
6Slice one red onion and three different colored bell peppers (e.g., red and yellow) into strips.
7Add the sliced onion and bell peppers to the mixing bowl with the chicken.
8Add 2 teaspoons of freshly minced garlic to the chicken and vegetables.
9Pour the fajita seasoning mix over the chicken and vegetables.
10Add 2 tablespoons of olive oil to the mixture.
11Toss all ingredients together with tongs until everything is evenly coated.
12Spread the seasoned chicken and vegetables onto the prepared baking sheet, ensuring an even layer.
13If the sheet pan is too crowded, use another sheet pan to spread the ingredients further.
14Bake in a 400-degree Fahrenheit oven for about 15 minutes.
15After 15 minutes, stir the mixture and cook for a little bit more.
16Once out of the oven, squeeze fresh lime juice over the fajitas.
17Warm up some tortillas.
18Serve the fajitas with warm tortillas and any desired toppings, such as sour cream.